The right of priority under 35 U.S.C. xc2xa7119(a) is claimed based on German Patent Application No. 101 26 221.3, filed May 30, 2001, the entire disclosure of which is hereby incorporated by reference.
The invention relates to a heat exchanger for an air-conditioning system of a motor vehicle and to an air-conditioning system.
It is the aim of motor vehicle manufacturers to reduce the fuel consumption of the vehicle. One measure for reducing fuel consumption is to switch off the engine during a temporary standstill, for example, when stopping at traffic lights. This is also called idle stop operation. This measure is already used in the case of modern, low-consumption vehicles, such as, for example, in the xe2x80x9cthree liter vehiclexe2x80x9d. In the case of vehicles which have the idle stop operating mode, the engine is switched off for approximately 25-30% of the driving time in city traffic.
This is one reason why vehicles of this type are not equipped with an air-conditioning system, since when the engine is at a standstill it is also not possible to drive the compressor that is necessary for the air-conditioning system, and so an air-conditioning system cannot provide the necessary refrigeration output in the idle stop operation.
In order to solve this problem, it is proposed in EP 0 995 621 A2 to ice up the evaporator of the air-conditioning system by means of the condensate that arises when moist air cools, with the result that, in the idle stop operation when the engine is switched off, the air can be cooled by the ice which then thaws. However, this method has numerous disadvantages. The quantity of water that is present in the air and which is necessary for icing up the evaporator depends on the climatic environmental conditions. Thus, when there is little air humidity, there may not be sufficient condensation water for the icing up. Furthermore, as a rule, a relatively long period of time is required in order to ice up the evaporator, and therefore this known air-conditioning system can only work in the idle stop operation after a relatively long driving period.
A further problem is that, as a rule, the evaporator ices up unevenly, and consequently the evaporator has regions that are iced up and regions that are not iced up. Furthermore, the icing up may be so severe that the air cannot flow through the evaporator or can flow through only with a high loss of pressure. The layer of ice always produces a loss of pressure from the air, which results in the need for an increased blower output. Another disadvantage is that bacteria easily collect on moist surfaces and can cause unpleasant odors.
One object of the present invention is to provide an improved heat exchanger for a motor vehicle air-conditioning system.
Another object of the invention is to provide an improved automotive air-conditioning system.
A further object of the invention is to provide an improved method for air-conditioning the passenger compartment of a motor vehicle.
In accordance with one aspect of the present invention, there has been provided a heat exchanger for a motor vehicle air-conditioning system, comprising: a plurality of conducting members for a refrigerant, spaced apart to permit air flow between them for heat exchange purposes; and at least one storage member penetrating the conducting members and designed to contain a storage medium for storing cold extracted from the refrigerant.
In accordance with another aspect of the invention, there is provided an air-conditioning system for a motor vehicle, comprising a compressor and an evaporator, wherein the evaporator comprises a heat exchanger as defined above.
According to still another aspect of the invention, there has been provided a method for air-conditioning a passenger compartment of a motor vehicle, comprising: providing an air-conditioning system as defined above; while the compressor is operating, storing cold in the storage medium contained in the storage members; and at least while the compressor is not operating, extracting cold from the storage medium contained in the storage members to air-condition air provided to the vehicle passenger compartment.
Further objects, features and advantages of the present invention will become apparent from the detailed description of preferred embodiments that follows, when considered together with the accompanying figures of drawing.